Railway signaling system



F. L. Donesom, RAILWAY SIGNALING SYSTEM.. APPLICATION FILED JULY I, 1916.

1,352,793. I PatentedS ept. 14,1920;

A INVENTOR TTOR/VEY UNl'IEDfiSTATES PATENT OFFICE.

FRANK L. DODGSON, OF ROCHESTER; NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNALCOMPANY, F GATES, NEW YORK, A CORPORATION OF NEW YORK,

RAILWAY SIGNALING SYSTEM.

Application filed July 1,

T0 all-whom it may concern:

Be it known that I, FRANK L. DODGSON, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented new and useful Improvements in Railway Signaling Systems, of. which the following is a specification.

This invention relates to railway signaling systems and more particularly to such systems using normally closed track circuits.

The main objects of my invention are to insure the intended operation of the'track relays under all of the varying conditions of practice,,both' as regards the deenergization of the relays so as to insure the dropping of the relay armatures and also as regards the proper energization of the relays and movement of the armatures to their normal raisedposition; and the accomplishment of these results with a minimum ex endi-- ture of energy in the track circuits. y invention fulfils these objects, giving certainty of proper operation under all conditions in an economical and efiicient manner. Other objects and advantages which are obtained by my invention will be understood by those skilled in the art.

One factor of difficulty with track circuits is the variation in ballast resistance which occurs under practical service .conditions and another difficulty is the variation in the amount of the shunt resistance when a train is in the block section, which shuntpath should of course always cause they deenergization of the relay so as to cause it to drop its armature. The resistance of the shunt path formed by the presence of a car in the block, not only varies relatively to the relayaccording to-the position of the train in the block, but also depends upon the condition of the surface of the rails and car wheels, the presence of rust, or ale, and the like causing variation of the shunt resistance.

Another factor affecting the operation is that when'the relay armature is in its lowest position, the energy in the relay coils which is necessary for moving the armature to its attracted position is greater than the energy which is necessary to retain the armature in its attracted positionp Thisresults in the expenditure of considerable energy when the armature is in its normal Specification of Letters Patent. Patented Sept, 14, 1920 1916. Serial No. 107,019. I

position and also necessitates such a low shunt resistance to insure the deenergization of the relay sufficiently for causing its armature to drop, that the relay under some conditlons-fails to act upon the entry of a train in the block section. r

It has been proposed to insert a resistance 1n series with the relay coil by control of its relay contacts when the relay armature leaves its lowest position, but this has proven of no practical utility, because if the amount of the resistance is sufiicient for securing any practical advantage in overcoming the above difiicultles, it results in a continuous vibration of the relay armature when no train is in the block section, especially under condi-.

tions of low ballast resistance with resultant low voltage at the relay. This is because the armature as soon as it leaves its back contact inserts the resistance in the circuit of the relay coil and consequently so reduces the strength of current through the relay coil that it is not sufficient to complete the movement of the armature to its attracted position resulting in the armature dropping to its lowest position; this in turn cuts out the resistance, causing the current strength in the relay coil to be sufficient to again raise the armature, which then falls, due to the insertion of the resistance, and so on giving a vibratory movement which of course renders the suggestion useless for any practical service.

It has also been proposed to utilize the two coils of the relay in a series and parallel connection relatively to each other, utilizing the parallel connection of the coils when the relay armature is in its lowest position and for raising the armature to its attracted position, and utilizing the series connection of the coils for retaining-the armature in its attracted or raised position. This has proven to be of no practical benefit, because when the relay coils are properly Wound in relation to the track circuit voltage,'the ballast resistance and shunting resistance of the train for properly picking up the armature upon the exit of a train from the block section, the series connection of the coils then gives such a reduced amount of energy for holding the relay armatureQthat it is in-' suflicient, especially when under variation ,of the ballast resistance the voltage at the relay has become comparatively low. The result arrangement totally useless for practical application to the closed track circuit system.

By my invention these difiiculties are en tirely overcome and the objects and advantages fulfilled as above stated.

My invention will be understood by reference to the following description and the accompanying drawings, in which Figure 1 is a dia rammatic illustration of one embodiment o my invention, and Fig. 2 is a diagrammatic illustration of a modified form of my invention. I

Referring first to the embodiment of the invention shown in'Fignl; the numerals 1 and 2 designate the track rails of a track section orblock A, thesep'arate rail sections thereof being suitably bonded together in the Well known manner, and being separated from the track rails of the adjacent track sections or blocks by insulating joints 3. A

source offelectro-motive force, illustrated as a battery 4, is connected across the track rails 1 and 2 near one end of the block A, and at the other end of said block a track relay R has one terminal of its coils or windings connected by a conductor 5 to the track rail 2, the other terminal of the coils of said track relaybeing connected by-conductor 6,

adjustable resistance 7, and conductor 8;

to the track rail 1.

Associated with the track relay. R is an auxiliary relay 9 having the usual armature which controls two contact fingers shown conventionally in the .drawing and designated 10 and 11. In this connection it is noted that relays are. ordinarily provided with only one armature, properly speaking, which armature ,is connected to and operates any number er contact fingers desired; but

it should be understood that. a relaymay have two or more armatures, each controlling a circuit, and in "the descri tion hereinafter given the words contact fiinger are intended to include a separate armature. The

contact finger 10 governed by the auxiliary relay 9 controls a shunt path of relatively low res stance around the resistance 7, said shunt path comprising conductor 12,.con-' tact finger 10 in its lower position and conductor 13. The contact finger 11 of the auxiliary relay 9 isshown as controlling a signal S for governing traflic over the block A, said signal being shown as the normally clear type and having a controlling circuit which may be traced as follows: eommenc 19 back to the battery 14.

R being in its upper position, the auxiliary or danger.

ing' at the battery 14, conductors 15 and 16, contact finger 11 in its upper position, conductor 17, operating mechanism of the signal S (not shown) and conductors 18 and The track relay R is shown as provided with the single armature or contact finger 20 which controls'the circuit for energizing the; auxiliary relay 9, which circuit may be traced as follows: commencing at the battery 14, conductors 15 and 21, auxiliary relay. 9, conductor 22, armature 20 in its upper position and conductors 23 and 19 back to the battery 14:.

Referring to the operation ofthe embodiment of the invention illustrated in Fig. 1, the parts are shown in the position which they assume when no train is present in the block A, the armature 20 of the track relay relay 9 being energized, and the resistance 7 being included in the connections between the track .relay R and the track rails 1 and 2. When a train enters block section A, the armature 20 of the track relay R drops and interrupts the circuit hereinbefore tracedfor energizing the (auxiliary relay 9, thereby causing the contact fingers 10 and 11 of said relay 9 to drop to'their lower position. The deenergization of the auxiliary relay 9 .may be used to control any suitable signaling device, or may be used to perform any desired function; but in the particulararrangement shown in Fig. 1, the dropping'of the contact finger 11 of said relay 9 interrupts the circuit for the'operating mechanism of the signal S, thereby causing the signal S to assume its biased position and indicate stop When the contact finger 10"of the auxiliary 165 relay 9 drops it establishes a relatively low resistance shunt path around the resistance 7, so that the resistance 7 which was formerly included in the connections between the track relay R and the track railsl and 2, is now excluded from said connections; and when the train leaves the block A the connections between the relay R and the track rails 1 and 2 include the minimum amount of resistance, so-that suflicient current can be derived from the minimum electro-mofingers 10, 11, causing the resistance 7 to be inserted in series with track relay R and also causing the signal -S to be moved to its proper position. I Adjustment of the resistance 7 to a proper amount is important in securing the full its 120 sistance is short circuited when the track relay armature is in its lowest position,

and remains short circuited until the track relay armature has,been fully raised to its tice, thus giving certainty of proper uppermost position, it offers no impediment to the economical utilization of the energy from the track circuit in the track relay for raising its armature as soon as the .car or train has passed outof the block section. For insuring the proper raising of the armature the relay must be properlywound and proportioned in relation to the track circuit and the value of the electromotive-force impressed upon the track circuit must be adjusted to insure the raising of the armature under the worst ballastture is in its raised position, the current flow will be just suflicient to. insure the holding of the armature of the track relay in its upper position, due allowance, as may be found desirable, being made for varia tions in ballast resistance, variations in voltage applied to the portion of the circuit containing the track relay and other conditions which may occur in practice.

It is evident that with these conditions the amount of energy consumed in holding the relay armaturejn its upper position when no train is in the block is much reduced compared with the amount which would be necessary if the resistance 7 were not utilized, thereby securing economy of energy when no train is in the block. F urthermore it is necessary to shunt only a small part of the current flowing in the coils of the track rela in order to cause its armature to drop. onsequently when the train enters the block, although the track rails may be rusted or dirty, or other conditionsmay be such thatthe resistance of the shunt established by the wheels and axles of the train is comparatively high, nevertheless. sufficient current will be shunted from the coils of the track relay to insure the dropping of the track relay armature under all the variable conditions of pracoperation of the signals;

In the modification shown in Fig. 2 the function performed by the contact finger 10 of the auxiliary relay-9 is performed by a circuit controller'24 operated by the signal S. This circuit controller 24 is-illustrated conventionally, and is closed when V the signal S is in "its horizontal or danger I position, so that when the block A is occupied by a train and the signal S is in its horizontal position, the circuit controller 24 is closed and establishes a relatively low resistance path comprising conductors 25 and 26, and the circuit controller 24, around the resistance 7.

Fig. 2 is determined and adjusted in the The resistance 7 shown in The operation of the modified arrangement of circuits and controlling devices shown in Fig. 2 is in effect the same asthe. operation of the arrangement shown in Fig. 1, except that in the arrangement shown in Fig. 2 the shunt for the resistance 7 is established by the operation of the circuit controller 24; whereas, in the arrangement shown in Fig. 1, the shunting of the resistance 7 is accomplished by the deenergization of the auxiliary relay 9.

It should be noted that in both of the arrangements shown the resistance 7 is not included in the circuit for the coils of the track relay R until the armature of said track relay has been raised to its uppermost position, since it is evident that in the arran ement shown in Fig. Ll the armature 20 of the track relay R must be raised to its upper position before the auxiliary relay 9 is energized, and that the shunt around the resistance 7 is not broken until said auxiliary relay contact finger 10- is raised. n a similar way, in the arrangement shown in Fig. 2, the armature 20 of the track relay R must be raised to its upper position before the circuit for operating the signal S is completed, and it is apparent that the shunt path around the resistance 7 is not broken until the signal S is operated toward its clear position and the circuit controller 24 is actuated thereby.

By reason of this construction, it is assured that the resistance 7 will never be in-. serted in circuit with the relay coils until vthe armature 20 has been raised to its upper- 9 is ener ized and its armature varies in its different positions between the lowermost position and the uppermost position, thisvariation being vdue to the change in the air gap between the armature and the pole pieces. With the armature of a relay in its lowermost position, the amount of current flowing in the relay coils, required to cause the armature to commence its upward movement, is the greatest; and as the air gap between the armature and the pole pieces is reduced by the approach of the armature more and more .to its upper- I most position, the current required to continue the movement of the armature may be decreased. As explained he reinbefore, for

the purpose of economy and safety, it is de. sirable to reduce the current flowing in the relay coils as much as possible when the relay armature is fully raised, the ideal object sought to be obtained being that in which the current is reduced to an amount just sufficient to retain the armature in its raised position. This desirable result cannot be accomplished if the resistance is inserted in circuit with the relay coils by the armature of the relay itself, for the reason that the current cannot be reduced, when the armature is only partly raised, to the extent desired, without causing objectionable vibration of the relay armature. When, however, provision is made, as in my invention, for inserting this resistance in the circuit only after the relay armature has completed its movement to its attracted position, the resistance 7 maybe adjusted to give the best results, and at the same time the objectionable vibration of the armature is avoided. Furthermore, according to this invention, there is no possibility of an objectionable vibration of the relay armature when ballast conditions become exceptionally bad, because the relay armature, it will be attracted at all, will be held in its attracted position when the resistance 7 is inserted in cirnuit.

It is also characteristic of this invention that the resistance 7 is not cut out ofv the circuit upon shunting of the relay until the relay armature has reached its lowermost position, thereby assuring that this resistance will not interfere with the complete dropping of the armature. In the arrangement shown. in Fig. 1 the resistance 7 is not shunted until after the contact finger 10 of the auxiliary relay 9 falls to its lower position, and that this will 'not occur until after the armature 20 of :the track relay R has dropped to its lower position, providing thatconstruction shown in Fig. 2. In the arrangement shown in Fig. 2, the shunt around the resistance-7 is notestablished until after the armature 20 of the track relay R has dropped farenough to interrupt the circuit for the signal S, and until the signal S has assumed its horizontal or danger position and closed the circuit controller 24; and since the time required for the signal S to move from its vertical position to its horizontal position is long compared with the time required for the armature 20 of the track relay R to move from its upper position to its lower position, it is assured that the "resistance 7 will not be shunted until the armature 20 of said track relay has reached its lowermost position.

Also, in the. arrangement shown in Fig. 2,

the resistance 7 is not shunted until the signal S reaches its horizontal or danger position, that is, the operating characteristics of the track'relay R are not changed until the signal S has properly respondedto, the control of said track relay.

Although I have particularly described the construction of one physical embodiment of my invention, and explained the operation and principle thereof; nevertheless, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodlments of the idea "of, means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a signaling system for railways, a track circuit comprising a source of electromotive force and a relay, a resistance external' to the windings of the relay and adapted to reduce the current through the relay windings to a predetermined value corresponding approximately to that required to maintain the relay picked up, and

circuit controlling means responding to the operation of the relay for inserting said resistance in. series with the relay windings without interrupting the path of current through said windings, said means lagging in its operation behind themovement of the I relay armature and acting to insert said resistance only after said armature has attained its fully attracted position.

1 2. In a signaling system for railways, a"-

track circuit comprising a source of electromotive force and a relay, a resistance external to the windings of. the relay and adapted to reduce the current through the relay windings to a predetermined value corresponding approximately to that required to maintain the relay picked up, an

circuit controlling means governed by the relay armature for inserting said resistance in series with the relay windings only after said armature has fully attained its attracted position and for excluding said resistance from the path of current through said windings when the armature has fully attained its retracted/ position, said means ternal to the windings of the relay and adaptedto reduce the current through the relay windings to a predetermined value corresponding approximately to that required to maintain the relay picked up, and automatic means separate from the relay and set into operation when the relay armature fully attains its attracted position for inserting said resistance in series with said windings without interrupting the flow of current through said windings,

4. In a signaling system for railways, a track circuit comprising a source of electromotive-force and a relay, a resistance external to the windings of said relay, a movable device for controlling the inclusionand exclusion of said resistance in and from the path of the main circuit through the windings of said track relay, and means for causing said movable device to be controlled upon the movement of the armature of said relay to its extreme positions.

5. In a signaling system for railways, a track circuit comprising a source of electromotive-force and a relay, a resistance external to the windings of said relay, a second relay having its windings energized and deenergized by movement of the armature of said first relay, and means controlled by said second relayjor inserting and cutting out said resistance from-the path ofithemain current through said first relay.

6'. In a signaling system; for railways, a track circuit comprising a source of electromotive-force and a relay, a resistance ex: ternal to the windings of said relay, and

. means separate from the relay and con- I treme positions.

trolled thereby for inserting and cutting out said resistance from the path of the main current through said first relay only after the armature thereof-has attained its ex- 7. In a signahng systemfor railways, in

' combination: a track circuit including a section. of bonded track rails and a source of electro-motive force connected across sald track rails at one end of the section, a trackrelay connected to the track rails at the other end of the section, means external to the windings of the relay and adapted to limit ings for rendering said first mentioned means efi'ective only after the relay armatively.

ture has attained its fully attracted position and without interrupting the flow of current throughsaid relay windings.

8. In a signaling system for railways, a track circuit comprising a source of electromotive-force and a relay, means external to the relay windings for limiting the attractive force of the relay upon its armature to an amount sufiicient to hold the armature of said relay in its raised position but insufficient to raise said armature from its lowest position, and controlling means for causing said first named means to be effective and ineffective respectively only when the armature of said relay is in its fully attracted position and in its fully retracted position, said means both acting to maintain a path for current to fiow through the relay windings at all times.

9. Ina signaling system for railways, the combination with a track circuit including a source of current and a relay, of an adjustable resistance external to the windings of therelay and adapted to reduce the current through said windings to a predetermined value, circuit controlling means for connecting said resistance into and out of the circuit through the relay windings without at any time interrupting the flow of current through said windings, and electromagnetic means controlled by the relay armature for operating said circuit controlling means, said electromagnetic means acting to operate the circuit'controlling means only after the completion of the movement of 1'00 therelay armature to its extremepositions.

10. In a signaling system for railways, in combination a track circuit including a section of track rails and a source for impressing anelectromotive-force across said track said connections approximately in accord ance with the difference between the pickup and holdup currents for said relay, said means acting to chan e the resistance only after the armature 0 said relay has been raised to its uppermost position and without atvany time interrupting said connections; and means for signaling controlled by said track relay.

11. In a signaling system for railways, a track circuit including a source of current and a relay, a resistance external to the windings of the relay and connected in series therewith, a second relay having its energizing circuitcontrolled by a front contact of the track relay, anda low resistance shunt for said resistance opened and closed when said second relay-picks up and drops respecsistance in the connections between the track relay and the track rails, a low resistance shunt for said reslstance, blased electromagnetic means for opening and closing 'said, shunt When energized and deenergized respectively, and a circuit controlling said track relay,'whereby said adjustable resistance is included and excluded from the circuit through the track relay Without interrupting the path for the flow of current through the relay and only after the relay 1 5 armature has attained its extreme positions.

FRANK DoDGsoNV means and including a front contact of the: 10 

